Etude multiéchelle de la dégradation des roches par la cristallisation de sels dans les réseaux por - Page 1 - test Tous nos livres sont imprimés dans les règles environnementales les plus strictes Il est interdit de reproduire intégralement ou partiellement la présente publication sans autorisation du Centre Français d’exploitation du droit de Copie (CFC) – 20 rue des GrandsAugustins – 75006 PARIS – Tél. : 01 44 07 47 70 / Fax : 01 46 34 67 19. © Éditions Edilivre – Collection Universitaire – 2008 ISBN : 978-2-8121-0022-2 Dépôt légal : Août 2008 Tous droits de reproduction, d’adaptation et de traduction, intégrale ou partielle réservés pour tous pays. ECOLE DOCTORALE SCIENCES ET INGENIERIE de l’université de Cergy-Pontoise THESE Présentée pour obtenir le grade de docteur d’université Spécialité : Géologie - Sciences de la Terre Multiscale study of stone decay by salt crystallization in porous networks Etude multiéchelle de la dégradation des roches par la cristallisation de sels dans les réseaux poreux Matthieu Angeli Université de Cergy-Pontoise Département des Sciences de la Terre et Environnement Laboratoire de tectonique UMR 7072 Soutenue le 16 novembre 2007 Devant le jury composé de : Pr. François Renard (Université Joseph Fourier, Grenoble) Pr. Carlos Rodriguez-Navarro (Universidad de Granada) Pr. Christian David (Université de Cergy-Pontoise) Dr. Beatriz Menéndez (Université de Cergy-Pontoise) Dr. Jean-Philippe Bigas (Chryso, Sermaises) Pr. Albert Noumowe (Université de Cergy-Pontoise) Dr. Jean-Didier Mertz (LRMH, Champs sur Marne) Dr. Michael Steiger (Universität Hamburg) Rapporteur Rapporteur Directeur de thèse Co-directeur de thèse Co-directeur de thèse Président du jury Examinateur Examinateur ACKNOWLEDGEMENTS First I would like to thank my PhD directors, Christian David, Beatriz Menéndez and Jean-Philippe Bigas, who helped me during the three years and gave me the opportunity to choose the direction of my work. The beginning of the thesis was quite difficult and they helped me find a topic that would make me work during these three years. I also would like to thank the other members of the laboratory who have worked with me during these years: Ronan Hébert mainly, Philippe Robion and also Laurent Louis during the final year. Their knowledge in the microstructure analysis of the stones greatly helped me to understand what the point of my work was. During the beginning of my thesis, the visit of two laboratories allowed me to discover what was an experimental laboratory working on the weathering of the stone: the LISA in the University Créteil-Paris XII (Laboratoire Inter-universitaire des Systèmes Atmosphériques) and the LRMH in Champs-sur-Marne (Laboratoire de Recherche sur les Monuments Historiques). I would like to thank all the people that have welcomed me in these laboratories and kindly explained me what their research was about: Roger Lefèvre, Anne Chabas, Patrick Ausset and Tiziana Lombardo from the LISA, Jean-Didier Mertz from the LRMH. During these three years I have met many people working in the field of stone weathering. I had very interesting discussions with some of these researchers, discussions which helped me to take a step backwards and see how my work could fit in the general research about stone weathering. I am very grateful for this to David Benavente from Alicante; Muzahim Al-Mukhtar, Kevin Beck and Thua Tri Van from the CRMD in Orléans (Centre de Recherche sur la Matière Divisée); and Michael Steiger from Hamburg. I would like to thank Carlos Rodriguez-Navarro (University of Granada) and François Renard (University of Grenoble) for accepting to review my work, Albert Noumowe from the Civil Engineering department in the University of Cergy-Pontoise for accepting to be the president of the jury, and also again Jean-Didier Mertz and Michael Steiger for accepting to be in my jury. I always had a lot of support from all the people from my laboratory, during good and bad times. The general atmosphere was very friendly and favourable to a good work. For this I would like to thank: Siegfried, Bertrand, Jean-Marc, Jean-Christian, Béatrice, Charly, Danielle, Pascale, Paul- Emile and Dominique. This thesis would not have been the same without the support of other PhD students or former PhD students, especially during the hard time of the final redaction: Yves, Nicolas and Fabien in Cergy, and also Matteo and Virginie during the first year; William, Cédric, Thomas and Pipo (les professeurs); Martin, Elo, Béné, Laetitia, Ben, Louise, Kristell, Agnès and many others in Paris. And finally, I would like to thank my parents, my sister and especially Alex. General introduction on salt decay _____________________________________________ 3 Outline of thesis ____________________________________________________________ 4 Chapter I: Decay of natural stones _____________________________________________ 7 1. Weathering agents ______________________________________________________ 9 1.1.Salt decay ________________________________________________________ 9 1.1.1.Efflorescences_________________________________________________ 10 1.1.2.Contour scaling _______________________________________________ 10 1.1.3.Granular disintegration _________________________________________ 11 1.1.4.Honeycomb weathering (also called alvéolisation) ____________________ 11 1.2.Freeze and thaw __________________________________________________ 11 1.3.Thermal shock ___________________________________________________ 13 1.4.Water streaming __________________________________________________ 13 1.5.Atmospheric pollution _____________________________________________ 14 1.5.1.Soiling _______________________________________________________ 14 1.5.2.Gypsum crusts ________________________________________________ 14 1.5.3.Acid rains ____________________________________________________ 15 1.6.Biological colonisation_____________________________________________ 15 2. Influence of the stone characteristics on weathering __________________________ 16 2.1.Mineral composition_______________________________________________ 16 2.2.Hydric properties _________________________________________________ 17 2.2.1.Fluid flow ____________________________________________________ 17 2.2.2.Hydric dilation ________________________________________________ 17 2.3.Strength contrast__________________________________________________ 18 2.4.Stone-stone and stone-mortar compatibility ____________________________ 19 3. Building characteristics _________________________________________________ 20 3.1.Location of stones_________________________________________________ 20 3.2.Sheltered zones ___________________________________________________ 21 3.3.Mechanical load __________________________________________________ 22 4. Human causes_________________________________________________________ 22 Chapter II: Materials and methods ____________________________________________ 25 1. Overview of the studied stones ____________________________________________ 27 1.1.Lutetian limestones________________________________________________ 27 1.2.Pierre de Souppes _________________________________________________ 30 1.3.Fontainebleau sandstones __________________________________________ 31 1.4.Chinese sandstone ________________________________________________ 32 1.5.Agra sandstones __________________________________________________ 32 2. Microstructural studies__________________________________________________ 33 2.1.Characterization of the studied stones_________________________________ 34 2.1.1.Optical microscopy_____________________________________________ 34 2.1.2.Porosity______________________________________________________ 40 2.1.3.Mercury porosimetry ___________________________________________ 41 2.1.4.Helium pyknometry_____________________________________________ 46 2.1.5.Discussion about porosity _______________________________________ 47 2.1.6.Specific surface area ___________________________________________ 49 2.2.Geophysical properties _____________________________________________ 49 2.2.1.P-waves velocity_______________________________________________ 50 2.2.2.Magnetic Susceptibility _________________________________________ 51 2.2.3.Analysis of results______________________________________________ 53 3. Hydromechanical properties _____________________________________________ 55 3.1.Hydric tests ______________________________________________________ 55 3.1.1.Water Absorption Capacity ______________________________________ 55 3.1.2.Capillarity____________________________________________________ 56 3.1.3.Evaporation __________________________________________________ 57 3.2.Mechanical tests __________________________________________________ 60 4. Accelerated ageing by salt decay __________________________________________ 60 Chapter III: Salt crystallization_______________________________________________ 63 1. 2. 3. Experimental results____________________________________________________ 65 Theories of salt damage _________________________________________________ 66 Sodium sulphate_______________________________________________________ 68 3.1.Mechanism of damage _____________________________________________ 68 3.2.Thermal recording during experimental weathering of limestones: the role of imbibition on salt crystallization and rock decay (article1; Journal of crystal growth) ___ 69 Chapter IV: Salt damage ____________________________________________________ 97 1. Macroscopic experiments________________________________________________ 99 1.1.Durability estimation ______________________________________________ 99 1.2.Crystallization of salts in pores: quantification and estimation of damage (article 2; Environmental geology)__________________________________________________ 100 1.3.Effects on mechanical strength _____________________________________ 121 2. Microscale experiment:Modification of the porous network by salt crystallization of experimentally weathered sedimentary stones (article 3; Materials and structures)_____ 122 Chapter V: Influence of environmental parameters______________________________ 161 1.Influence of capillary properties and evaporation on salt weathering of sedimentary rocks (article 4 ; HWC 2006) _____________________________________________________ 163 2.Influence of temperature and salt content on the salt weathering of sedimentary rocks (article 5; GSL special publication)___________________________________________ 185 Conclusion ______________________________________________________________ 207 Perspectives______________________________________________________________ 209 References _______________________________________________________________ 215 GENERAL INTRODUCTION ON SALT DECAY General introduction on salt decay Crystallization of soluble salts in porous networks is a major source of decay for natural stones (Goudie and Viles 1997). It is known as a major cause of erosion that shapes the landscapes from polar valleys (Prebble 1967) to arid regions (Beaumont 1968) and coastal areas (Mottershead 1982). It is responsible for the development of many geomorphological features like honeycombs, tafoni or pedestal rocks (Rodriguez-Navarro and Doehne 1999). It has even been proposed as the cause of erosion on martian landscape (Malin 1974; Rodriguez-Navarro 1998). But its effect is not limited to natural environments: natural building stone used in recent or historical buildings also suffer heavily from salt decay (Goudie and Viles 1997; Winkler 1997; Rodriguez-Navarro and Doehne 1999; Ruiz-Agudo et al 2007). This phenomenon is known since antiquity: Herodotus (about 440BC, translation from 1972) has reported it in the Nile Valley in his book “The histories”: “salt exudes from the soil to such an extent it affects even the pyramids”. Although this problem has been seriously studied since the 19th century (Turner 1833), the mechanism at stake is yet only partially understood. A reason for this lack of knowledge could be that this mechanism comes into the field of several sciences: rock physics and mechanics, civil engineering, geochemistry and thermodynamics. The importance of this topic comes from the fact that it has applications in various topics, from the conservation of historical monuments (the basis for this study) to the study of reservoir rocks, without forgetting geotechnics or CO2 storage. The presence of cracks and salt crystals in the porous networks has a direct influence on the fluid flow in sedimentary stones, as well as on their mechanical strength. For instance a good understanding of the crystallization processes could help to improve oil recovery rate in reservoir rocks, or help finding stone treatments to prevent damage from crystallization of salts in cultural heritage. The aim of this PhD is to understand the decay from a rock mechanics and rock physics point of view. Numerous theoretical studies have been led on the thermodynamics of salt crystallization under stress (Correns 1949; Wellman and Wilson 1965; Benavente et al. 1999, 2004a; Scherer 1999, 2004; Flatt 2002; Steiger 2005a,b). Nevertheless, there exist very few experimental attempts at confirming these theories. Sometimes, the theoretical results do not explain some facts that are observed on site or during accelerated ageing tests. For instance, the theory cannot explain why sometimes sodium sulphate is more destructive for 3
Etude multiéchelle de la dégradation des roches par la cristallisation de sels dans les réseaux por - Page 1
Etude multiéchelle de la dégradation des roches par la cristallisation de sels dans les réseaux por - Page 2
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